1. Field of the Invention
The present invention relates to the field of communications, and, more specifically, to a system and device which facilitate the transmission and receipt of voice data between a talker and a listener over the internet or other digital network in an interactive fashion.
2. Background Information
The invention described and claimed herein comprises a novel device to facilitate digital network telephony by connecting a standard telephone handset to a computer sound card so as to allow voice communication using an integrated microphone and speaker.
Recent advances in data compression technology have enabled transmission of voice conversations over digital networks, such as the internet or private digital networks. This is accomplished by providing at least two users with access to the internet and with computer hardware and internet telephony software. The hardware typically comprises a personal computer equipped with a sound card having both a “Line-In” or “Microphone-In” port and a “Line-Out” or “Speaker-Out” port, a microphone connected to the Microphone-In or Line-In port, one or more speakers connected to the Line-Out or Speaker-Out port; a central processing unit capable of converting analogue voice data to digital data and vice-versa; and means for transmitting and receiving data over a telephone line (typically a modem). Suitable internet telephony software includes COOL TALK(™), available from Netscape Communications or INTERNET PHONE VERSION 4.0(™), available from Vocaltec.
Such a system operates as follows. For simplicity, it is assumed that there are two users, a “talker” and a “listener”; in practice, the parties to a conversation change roles, but the process is the same with respect to the then-current talker and the then-current listener; in the case of full-duplex communication, each party may simultaneously be a talker and a listener. A talker's voice is captured by a microphone connected to the sound card interfaced with the local user's computer via the sound card's “Line-In” or “Microphone-In” line. It is then digitized and compressed, using the CPU and internet telephony software. The digitized and compressed data is then transmitted to the internet using a modem, where it is retrieved by the listener's computer, using a second modem. The listener's computer decompresses the data and feeds it to a soundcard having a line-out or speaker-out port connected to a speaker, where it is converted to analog form which may be heard by the listener.
This system offers the ability to use the internet infrastructure to carry voice conversations, with all the attendant advantages over written communications. However, as currently implemented, it suffers from at least four disadvantages.
The first disadvantage is the requirement of a microphone and at least one separate speaker, which require space and may be difficult to place so as to be convenient for use. The microphone in particular must be close enough to the user to receive a sufficient signal strength to survive the various processes and transmissions which are required, yet may interfere with operation of the computer if placed in its most natural location.
The locations of the microphone prevent the consistent and clear capture by the microphone of the local user's voice. The distance the local user's voice must travel from the user's mouth to the microphone diminishes the decibel level at which the user's voice reaches the microphone. This distance not only prevents the microphone from capturing the local user's voice when at low decibels, but allows background noise to enter into the sound stream captured by the microphone. This can result in both “choppy” and “dirty” captures of the user's voice that is transmitted to a remote user. Choppy captures occur when the talker lowers the decibel level of his or her voice below that which the microphone will recognize. This results in the word or words of lowered decibel level not being captured. The incompletely captured sentence is transmitted through the system to the listener's speaker or speakers. Thus, the remote user does not understand the meaning of the local user's communication because of its lack of completeness or “choppiness.” Dirty captures occur when the talker is in a setting where background noise is present. When the decibel level of the background noise reaching the microphone approaches or exceeds that of the talker's voice reaching the microphone, the resulting sound captured by the microphone is either of both the talker's voice and the background noise or solely the background noise. The resulting combination of voice and background noise or pure background noise that is then transmitted to the listener and rendered difficult or impossible to comprehend. In half duplex mode, background noise alone can “lock” the conversation into send-only mode where the user remote from the source of background noise cannot respond.
A related, but more serious disadvantage of a separate microphone and speaker is acoustic echo or feedback, generated when a microphone picks up the sound from a speaker and retransmits it to the talker, whose own microphone may pick it up and retransmit it to the listener and so forth.
Finally, separate speaker and microphone configurations make privacy of communications difficult and admit background noise, while also creating an unacceptably high level of background noise when used in a business environment.
Prior solutions to these problems have tended to work against each other. To prevent or reduce the poor capture of a talker's communication, the microphone's sensitivity has been increased. However, this increased sensitivity also increases the amount of background noise captured by the microphone and increases feedback problems. Similarly, to prevent or reduce the reception of background noise captured by the microphone, the microphone's sensitivity is decreased. However, this decreased sensitivity also decreases the quality and quantity of captured low decibel communications, resulting in “choppy” communications.